Hello, I have a question about partitions. How do I make a custom partition definition where a downstream asset needs 2 partitioned inputs. Eg. downstream is a partitioned asset for 2021 and required upstream asset for 2021 and 2020

I don’t think you’d want a custom partition. You can use a TimeWindowPartitionMapping to achieve this. https://docs.dagster.io/_apidocs/partitions#dagster.TimeWindowPartitionMapping You can search for “trailing window” in the slack channel to find a few relevant examples of people working through this issue

oh ok!